1. Field
This disclosure is related to the field of imaging.
2. Background of the Invention
When a digital video camera is aimed at a scene, it generates image data corresponding to the scene. The image data is then processed to produce an image of the scene.
An effort is made to improve the quality of the eventual image. The effort is made by adjusting some of the operating parameters of the digital video camera. Some adjustments are made by the user, and some automatically by the camera.
These operating parameters may include the pixel integration time, the gain, and the frame rate. The camera exposure parameters are the integration time and the gain. These parameters may be interrelated. For example, the integration time is currently determined, at least in part, by the luminance of the scene. If a scene starts becoming darker, the camera might correct for it by increasing the integration time.
There are a number of criteria used to determine video image quality. One criterion is the video frame rate (the higher the frame rate, the higher the quality). Another criterion is noise. The lower the noise, the higher the image quality. The noise is quantified as a Signal to Noise Ratio (SNR) (the lower the noise, the higher the SNR).
Often these two criteria are at odds. A higher frame rate requires a shorter integration time (and thus also a higher gain), which results in more noise (lower SNR). Achieving a higher SNR often requires a longer integration time, which in turn lowers the frame rate (and also requires lower gain).
In some situations, an image processing station is tethered to, and made to operate with, the digital video camera. The camera generates and simultaneously transfers the image data to the image processing station over the tether, which can be a data cable. This is referred to as a linked digital video camera.
Additional parameters may be adjusted in the situation where a digital video camera is linked. Some of these additional parameters are typically controlled by special software residing in the image processing station, sometimes called the camera client. One of these parameters is the frame rate of the image data flowing through the communication link. In many instances, the frame rate is not controlled directly, but only indirectly.
Sometimes the camera client requests the camera to transmit data at a specific frame rate. A digital video camera will attempt to deliver the frame rate requested by the camera client. Sometimes the requested frame rate is faster than can be accommodated by the bandwidth of the communication link. The requested frame rate will consequently not be provided.
The invention will become more readily apparent from the following Detailed Description, which proceeds with reference to the drawings, in which: